PP.09.20] AMBULATORY VASCULAR INDEX

Abstract

Objective: The current hypertension management involves both ambulatory blood pressure (BP) monitoring (ABPM) and evaluation of the arterial stiffness by measuring pulse wave velocity (PWV). Stiffness parameter β is a promising estimate of arterial stiffness characterized by a less dependency on BP. β is used to calculate the well-known cardio-ankle vascular index (CAVI), which is measured in the segment between heart and ankle. However, at present, CAVI may be obtained only at rest and thus may not return information on arterial stiffness in the dynamic conditions of everyday life. Recently available technologies now allow 24-h pulse wave analysis (PWA) integrated in ABPM devices and may provide an easy way to obtain PWV. They can also make possible to evaluate β in the corresponding segment and ambulatory BP in a single procedure. For methodological analogy with CAVI we decided to call new index AVI, which means Ambulatory Vascular Index. The aim of this part of the pilot study is to evaluate the features of the AVI in healthy volunteers. Design and method: Data of 179 healthy volunteers (BP and PWV) were collected with BPLab® ABPM device and validated Vasotens® PWA technology. AVI is calculated using BP and PWV of each measurement and then averaged for 24-h period. We used following formula: AVI = 2ρ/δP[lnPs/Pd]PWV2, where ρ: blood density, δP: Ps-Pd or systolic minus diastolic BP. Results: 24-h average AVI in volunteers was 15.4 ± 3.8, while 24-h average PWV was 9.3 ± 1.1 m/s (mean ± SD).There was no correlation between AVI and 24-h systolic BP (r = −0.02, n/s, fig.1, a), but 24-h PWV was significantly associated with SBP (r = 0.36, p < 0.05, fig.1, b). Both AVI and PWV were significantly related with age (r = 0.43, p < 0.05 and r = 0.42, p < 0.05, fig.1 c and d respectively). Conclusions: Our pilot study suggests that the AVI is a feasible estimate of arterial stiffness, with the advantage of being independent on BP. However, further study of the AVI feasibility, methods of calculation, and the role in integrated approach for evaluating aortic stiffness in relation to cardiovascular risk, are needed. AVI may be interpreted in similar way like other age-dependent indices of arterial stiffness.